1. Field of the Invention
Example embodiments generally relate to a transfer-fixing device, an image forming apparatus, and a transfer-fixing method, for example, for transferring and fixing a toner image on a recording medium.
2. Description of the Related Art
A related-art image forming apparatus including a copying machine, a facsimile machine, a printer, or a multifunction printer having two or more of copying, printing, scanning, and facsimile functions, forms a toner image on a recording medium (e.g., a sheet) according to image data by an electrophotographic method.
For example, a charger charges a surface of a photoconductor. An optical writer emits a light beam onto the charged surface of the photoconductor to form an electrostatic latent image on the photoconductor according to the image data. A development device develops the electrostatic latent image with a developer (e.g., toner) to form a toner image on the photoconductor. The toner image is transferred from the photoconductor onto a recording medium via an intermediate transfer belt. A fixing device applies heat and pressure to the recording medium bearing the toner image to fix the toner image on the recording medium. Thus, the toner image is formed on the recording medium.
However, when a recording medium having a rough surface is used, the intermediate transfer belt may not fully conform to the surface of the recording medium, and consequently a minute gap is formed between the intermediate transfer belt and the recording medium. As a result, abnormal electrical discharge occurs at the gap, and the toner image carried by the intermediate transfer belt is not properly transferred to the recording medium, resulting in a faulty image.
To address this problem, there are examples of a related-art image forming apparatus including a transfer-fixing device for performing a transfer process and a fixation process at the same time. Since the transfer-fixing device transfers a toner image to a recording medium while applying heat to the toner image, heated toner particles are softened and melted into a viscoelastic block-like clot, and fixed to the recording medium. Even when a minute gap is formed between a recording medium with a rough surface and a transfer-fixing belt, the clotted toner is fixed into the gap, thereby forming a high-quality image.
However, since the toner image is heated and melted by heating the transfer-fixing belt carrying the toner image, heat efficiency of the transfer-fixing belt decreases when the transfer-fixing belt has increased thickness for extended life or has a longer perimeter for use in a large-sized tandem type image forming apparatus. As a result, the transfer-fixing device may consume an increased amount of energy.
In addition to the above heating process, the transfer-fixing device performs a cooling process for cooling the transfer-fixing belt after the transfer and fixing processes in order to mitigate thermal damage to an imaging device. Therefore, repeated heating and cooling may cause the transfer-fixing device to consume an increased amount of energy.